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Post-annealing effects on the structural and optical properties of nickel vanadate thin films.
(2026-05-15)
Nedkun, Piyanooch
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Sangsai, Phannita
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Wongrat, Ekasiddh
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Chaiworn, Panupat
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Tubtimtae, Auttasit
Abstract This research gap is to understand the post-annealing-temperature-dependent structural transition and defect-mediated optical tuning in NiV₂O₆ thin films deposited using a spin-coating technique. By systematically correlating phase evolution, oxygen vacancy formation, and band gap modulation. The as-prepared thin films were annealed at 200 °C, 300 °C, 400 °C, and 500 °C. The annealing temperature of 400 °C was found for an amorphous structure with the band gap of 2.38 eV, which within an appropriate band gap of ∼ 2.3–2.6 eV for photoelectrochemical and electrochromic applications. Tuning of improved crystallinity with structural rearrangement and a lower band gap of 2.10 eV were obtained at 500 °C, which induced the diffusion of oxygen atoms and led to the formation of oxygen vacancies. This provides a clear processing–structure–optical property correlation and offers a simple-thermal route for band gap engineering without additional doping for enhancing the optical efficiency in solar absorber, optoelectronic, and photonic applications, particularly in broadband optical devices.
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Effect of pyrazine in PEDOT:PSS thin films: Structural, optical, optoelectrical, and electrical analysis
(2023-02-01)
Teesetsopon, Pichanan
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Treewut, Pattaraporn
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Sripetch, Sasithorn
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Nasomjai, Piyatida
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Tubtimtae, Auttasit
The pristine PEDOT:PSS and different weight amounts of pyrazine in PEDOT:PSS thin films were prepared using the doctor-blading technique on a borosilicate glass substrate. The structural, optical, and electrical properties of the effect of pyrazine in PEDOT:PSS thin films were presented for the first time of this admixed solution. More accuracy in the surface of thin films was observed by atomic force microscopy (AFM) which revealed the granular deposits on the film surfaces. Some hill shapes and the distribution of agglomerated grains were also observed on the thin films. The PEDOT:PSS with pyrazine has a preferred orientation to be an orthorhombic crystal structure. The crystallite sizes were reduced from 230.40 nm to 101.81 nm for 30–60 mg pyrazine in the PEDOT:PSS. The energy band gap (E<inf>g</inf>) value of pristine PEDOT:PSS is of 3.50 eV with Urbach energy (E<inf>U</inf>) of 336.10 meV. The alteration E<inf>g</inf> values from 3.52 to 3.67 eV was obtained with the estimated E<inf>U</inf> values in the range of 283.16–324.62 meV depends on various amounts of pyrazine. The linear optical parameters, i.e., the refractive index, optical electronegativity, real/imaginary dielectric constants, extinction coefficient, and optical conductivity were investigated and explained by the changes in the formation, nucleation, growth of clusters, and particle arrangement. As the spectrum increased, the highest χ(1), χ(3), and n<inf>2</inf> values were obtained for the 80 mg pyrazine in PEDOT:PSS of 0.110, 2.562 × 10−14 esu, and 6.219 × 10−13 esu, respectively. The electrical conductivity was clearly increased for pyrazine exceeding 40 mg from 1.85 × 102 to 3.84 × 102 S/cm and the figure of merit was in the range of 4.34 × 10−2 to 4.68 × 10−2 Ω−1. Thus, the novelty of this work can show that pyrazine in the range of 40 mg–80 mg is the optimum condition to synthesize non-linear optical (NLO) materials, organic light-emitting diodes (OLEDs), and organic light-emitting transistors (OLETs).
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Structural, optical, and electrical properties via two simple routes for the synthesis of multi-phase potassium antimony oxide thin films
(2022-07-15)
Homcheunjit, Ratchaneekorn
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Pluengphon, Prayoonsak
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Tubtimtae, Auttasit
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Teesetsopon, Pichanan
Multi-phase ternary oxide glass thin films of potassium antimony oxide were synthesized via dip coating (DC) and spray pyrolysis (SP) methods. The growth of thin film was conducted on a non-conductive borosilicate glass substrate. Surface morphology was investigated and showed different characteristics. X-ray diffraction (XRD) analysis revealed the peaks corresponded to the monoclinic KSb<inf>3</inf>O<inf>5</inf> and K<inf>2</inf>Sb<inf>4</inf>O<inf>11</inf> phases. The structural parameter analysis shows that the lower values of micro strain (ε), dislocation density (δ), and stacking fault probability (SF) with higher number (N) of particle in the multi-phase thin film for the spray pyrolysis method confirm slightly larger crystallite size, less crystal imperfection, and less structural disorder. The lower average transmission, absorption, and extinction coefficients resulted to higher refractive index, permittivity, and electrical susceptibility for the sample synthesized by a spray pyrolysis method. In addition, the average energy band gap values (E<inf>g</inf>) of 3.57 and 3.60 eV were obtained for the dip coating and spray pyrolysis methods, respectively. However, the lower R<inf>s</inf> (14.69 × 107 Ω/sq.) with higher σ<inf>h</inf> (85.09 S/cm) and the FOM<inf>(H-HR)</inf> (0.183 Ω-1) of the multi-phase K–Sb–O thin film for the dip coating method were obtained may be due to more interconnections generated at the interface and there are less residual on the surface of thin film.
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Response to comments on the paper, “Effect of low thermal treatment temperatures on the morphological, optical and electrical properties of Sn1-xMnxTe nanocomposite films incorporated with indium cations [Ceram. Int. 45 (2019) 23,203–23215]”
(2020-08-15)
Rukcharoen, Nuengruethai
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Tubtimtae, Auttasit
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Vailikhit, Veeramol
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Teesetsopon, Pichanan
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Kitisripanya, Nareerat
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Electrochemical performance of Bi2Te3 heterostructure thin film and Cu7Te4 nanocrystals on undoped and In3+-doped WO3 films for energy storage applications
(2020-05-01)
Buathet, Supitchaya
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Simalaotao, Kodchakorn
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Reunchan, Pakpoom
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Vailikhit, Veeramol
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Teesetsopon, Pichanan
We demonstrated the synthesis of undoped and In3+-doped WO<inf>3</inf> as an electron acceptor for energy storage applications, by utilizing the electrochemical S2− insertion/extraction process at the heterostructure of rhombohedral Bi<inf>2</inf>Te<inf>3</inf> thin films and hexagonal Cu<inf>7</inf>Te<inf>4</inf> nanocrystals. The cyclic voltammetry of heterostructured electrodes with and without In3+ doping both showed Faradic pseudo-capacitance behavior based on the oxidation and reduction processes. The largest exchange current density of 3.43 mA/cm2 was obtained for the heterojunction-structured-Bi<inf>2</inf>Te<inf>3</inf> thin films and Cu<inf>7</inf>Te<inf>4</inf> nanocrystals with In3+ doping in the WO<inf>3</inf> electrode. This implies more favorable hydrogen evolution reaction kinetics and higher electrocatalytic activity at the anode. The highest specific capacity of 90.2 mA h/g was obtained at a scan rate of 10 mV/s, with the power density reaching 1.7 kW/kg at the highest energy density value of 18.85 Wh/kg for the In3+-doped electrode. The overall results revealed the inherent properties of the new electrode materials, as well as their potential use in energy storage devices or in future electrochemical energy conversion and storage applications involving hydrogen (or oxygen) evolution reactions.
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Structural, optical and electrochemical performances of undoped and Sn2+-doped Bi2Te3 nanoparticles on WO3 electrodes
(2020-01-01)
Buddeesao, Mirantee
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Raknual, Duanghatai
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Tubtimtae, Auttasit
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Vailikhit, Veeramol
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Teesetsopon, Pichanan
A facile synthesis approach was used to prepare Sn2+-doped Bi<inf>2</inf>Te<inf>3</inf> nanospheres on a WO<inf>3</inf> electrode, and the pseudo-capacitive property was measured for samples prepared with optimum parameters. SEM micrographs revealed that after the Sn2+ doping, the morphology of Bi<inf>2</inf>Te<inf>3</inf> changed from aggregated or network-like nanoparticles to smaller nanospheres with a homogeneous distribution. The X-ray diffraction pattern showed rhombohedral Bi<inf>2</inf>Te<inf>3</inf> coated on the WO<inf>3</inf> electrode. Due to the more abundant electro-active sites and charge carriers that diffused through the electrolyte to the working electrode, the Sn2+-doped Bi<inf>2</inf>Te<inf>3</inf> electrode displayed the highest specific capacity of 41.4 mAh/g at a scan rate 10 mV/s, a power density of 0.63 kW/kg, an energy density of 24.5 Wh/kg, and an LSV breakdown potential of 0.26 V. These materials may be applied in potential pseudo-capacitors and in further energy storage devices.

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